The present invention relates to an optically variable areal pattern that can be provided, for example, in objects to be protected, such that the optically variable areal pattern permits the authenticity of the object to be verified, and/or serves as protection against unauthorized reproduction or imitation.
Optically variable areal patterns are known that mimic to a viewer, by means of microscopically small embossing patterns, the impression of a macroscopically bulged surface. A simple example is a metalized Fresnel lens that a viewer can perceive as a spherical surface. Further examples of more complex motifs are described, for example, in EP 1 562 758 B1.
From WO 2011/066990 A2 it is known to reconstruct a bulge having a plurality of small, reflective facets. Such areal patterns are well suited as security elements, since the optical effect is easy to understand and is easily visible also in poor lighting conditions, and since a reproduction with typographic means is not possible.
Due to the high attractiveness of the optical effects, they are used not only within the banknote field but, for example, also increasingly in the packaging industry. This is causing the special status of such effects as a security feature to dwindle, and the threat due to reproductions or imitations to rise.